Surge Protection

[LastManOnline]

A DNO supply fault this week resulted in damage to several electronic devices (audio equipment, chargers, appliances. USB ports sockets etc). My question relates to the best type of surge protection to negate the effects, not just of transient overvoltages, but of a prolonged overvoltage. It can take several hours for a supply fault to be rectified. Any suggestions appreciated

 

[snowhead]

Not a surge then , more a constant overvoltage situation?

The only way to protect from potential prolonged over / under voltage is to arrange auto disconnection of the supply when the voltage is out of range.
Voltage monitor and a contactor.

I used to work on petrol filling stations, not on the pumps but including the supplies to them.
They had overvoltage cut off on the supplies to the pumps originally, but it was removed as pupms came along with individual built in protection.

 

[LastManOnline]

Not a surge then , more a constant overvoltage situation?

The only way to protect from potential prolonged over / under voltage is to arrange auto disconnection of the supply when the voltage is out of range.
Voltage monitor and a contactor.

Thanks snowhead. Yes, it's a constant overvoltage situation. From what you say I conclude that standard surge protection is useless in these situations? That's means the customer is within his rights to seek compensation from the DNO

 

[snowhead]

My Son's house and a good few others nearby suffered loss of PEN a few years ago.
Western Power replaced everything that was damaged and anything that failed shortly after.
It was a good few thousand £'s for his house and many of the others.

W.P used a specialist company to do all the assesments, replacement / repairs.

 

[LastManOnline]

My Son's house and a good few others nearby suffered loss of PEN a few years ago.
Western Power replaced everything that was damaged and anything that failed shortly after.
It was a good few thousand £'s for his house and many of the others.

W.P used a specialist company to do all the assesments, replacement / repairs.

Very helpful experience.I strongly suspect the issue I experienced this week is similar. Waiting on confirmation from DNO. It's been educational from the point of view of coming to know the limitations of standard surge protection and being able to alert consumers to that.

 

[pc1966]

All normal SPD have limited energy handling, typically a few tens/hundreds of Joules and are intended for the order of 10kA for only 10us or so. They would just melt their thermal limits and become useless on a sustained over-voltage.

Now if only we had some sort of "smart" meter with a built-in cut-out that could disconnect on over/under voltage?

 

[LastManOnline]

Now if only we had some sort of "smart".... (device)... with a built-in cut-out that could disconnect on over/under voltage?

Firstly, thanks for the very helpful reply guys. Bottom line is SPD protect against transient overvoltages only. "Snowhead" alternative for "prolonged" overvoltages may not suit the budget of many domestic consumers. However I wondered if there might be a plug and play device available which would serve the same purpose and simply be plugged in to protect an appliance or some IT equipment??

 

[UNG]

Now if only we had some sort of "smart" meter with a built-in cut-out that could disconnect on over/under voltage?

Do I sense another regs amendment in the offing to mandate these devices

 

[pc1966]

Firstly, thanks for the very helpful reply guys. Bottom line is SPD protect against transient overvoltages only. "Snowhead" alternative for "prolonged" overvoltages may not suit the budget of many domestic consumers. However I wondered if there might be a plug and play device available which would serve the same purpose and simply be plugged in to protect an appliance or some IT equipment??

The likes of the Matt:E boxes for open-PEN protection disconnect on out-of-range volts so ought to do that. However, I only see the more expensive (£625) 3-phase version offering 100A pass-through.

If it were for a sub-set of circuits then the single-phase 32A version would be fine.

You don't have to use the earth disconnection if there is any risk the home might be a hazard without the CPC in place (i.e. you could just disconnect L & N).

 

[pc1966]

Do I sense another regs amendment in the offing to mandate these devices

Only if they actually work!

As far as I know they don't do any autonomous isolation, but they could do things like randomly stagger return after a power outage and isolate on out of range volts. I think they only isolate the L though, in which case they would offer some protection if it was fast acting.

Maybe I am wrong and such smartness already exists, but given the p-poor history of them so far I doubt it.